I don't want him to be Stefano's spawn. I'd prefer it remain John, since we've already suspended all logic to make it "work."
Failing that, I'd prefer, in order: Neil Curtis, Banksy, Daniel Scott, Peter Blake, [Can't Say Here], Brian Schofield, Emilio Ramirez, Shawn Brady*, Leopold Alamain, Tony Dimera, Ivan G'vais, Papa Hernandez, Curtis Brown, Nick Corelli, Sid Grayson*, Abe Carver, Josh Fallon, Chris Kositchek, Monty Dolan, Scotty Banning*
*-Yes, I know, these are Horton kin, but both distant enough to take (most) of the "ick" factor out of Paul's relationship with Will.
For more info, visit Specta-pedia. Seriously though, keep him John's son and there's a decade worth of story that we HAVE NOT seen. Switch him to a DiMeraling and we get same old, same old.
They could also make him bisexual at some point
Generally I would loathe a switcheroo like that, but it would be a nice first for Daytime TV, and would definitely open up story possibilities.
I forgot about the MadWorld angle. I'm a big fan of a mix of romance & other types of stories, he can be in the latter for awhile until they find the right "fit".